Here's the report from Caijing [English | Chinese]. There's a nice table at the bottom showing who got sentenced to what on what charges. The chairwoman and GM of Sanlu, Tian Wenhua, got life imprisonment for producing and selling substandard products (presumably Art. 140 of the Criminal Law, where a death sentence is not a possibility). Oddly, she was not convicted of producing and selling poisonous food (presumably Art. 144 of the Criminal Code, where a death sentence is a possibility), a charge that was the basis of at least one death sentence. It's hard to believe that had the procuracy charged her under Art. 144, she would not have been convicted; thus, it seems a decision was made early on not to charge her with a capital crime.

The other charge that brought death sentences was that of endangering public safety (presumably under Art. 115 of the Criminal Law, which speaks of causing injury or death through setting fires, cutting off water, explosions, spreading poison, or other dangerous methods). It's not an implausible stretch to apply Art. 115, but I wonder if this is the kind of thing the drafters had in mind; Arts. 140 and 144 seem a much better fit. Perhaps for some reason their premise of "producing or selling" was thought not to apply.